Switch



May 31, 1938. w. MURAD 2,119,022

SWITCH Filed oct. 11k, 1953 IN VEN TOR.

L 7:62 PAD BY 3,61

H/S ATTORNEY Patented May 31, 1938 UNITED STATES Pii'rlazm' ol-FlcisllllftoChnrlelS. Olli! Evans, San Francisco,

Application ombel- 11, im, sem No. 69ans My invention relates to aswitch, and more particularly to an electric switch. It is among theobjects of my invention to improve the operation and simplify theconstruction of electric switches.

Another object of my invention is to provide an improved mercury switch.

' A more speciilc object of my invention is to provide a mercury switchhaving a time delay action.

Still another object of my invention is to pro-- vide a mercury switchembodying quick-acting means for actuating the ilow of mercury.

Further objects of my invention include the provision, in a mercuryswitch of the character described, of an improved construction andarrangement of the mercury tumbler and its cooperating elements.

'I'he invention possesses other objects and features of advantage, someof which, with the foregoing, will be set forth in the followingdescription of my invention. It is to be understood that I do not limitmyself to this disclosure of species of my invention, as I may adoptvariant embodiments thereof within the scope of the claims.

Referring to the drawing:

Figure 1 is a vertical sectional view of a switch y embodying theimprovements of my invention;

and

bier in another position. y

Figure 3 is a detail perspective view of the barrier insert employed inthe tumbler shown in Figures 1 and 2.

Figure 4 is a longitudinal vertical sectional view taken through a.tumbler embodying a modified form of construction; and

Figure 5 is a longitudinal horizontal sectional vie'w of the same.

Figure 6 is a side view, partly in section and partly in elevation,-showing other improvements of my invention.

Figure 'l is a perspective view, partly in section and partly inelevation, showing further improvements of my invention.

Figure 8 is a horizontal sectional view through a tumbler embodyingstill further improvements of my invention.

- In terms of broad inclusion, the switch embodying my inventioncomprises a container or tumbler mounted for movement between open andclosed switch positions. Contacts are provided in the container, and aconducting body movable in the container is provided for bridging 55 thecontacts in the closed switch position. In

Figure 2 is a similar view showing the tum- (Cl. 20G-113) one form of myinvention I provide a solid conducting body, and in another form Iprovide a iluid body such as mercury. Quick-acting means are alsopreferably provided for shifting the container from one to another ofits switch positions to eil'ect rapid movement or iiow of the conductingbOdy In the mercurytype of switch I provide means for dividing themercury between the contacts, and in a special construction I alsoprovide means for retarding the mercury ow to give a time delay action.In order to provide a compact construction for the flush type of wallswitch I pivotally mount the tumbler behind the wall plate with thetrunnions also providing the contacts for the tumbler, and with portionsof the tumbler projecting through the plate to provide a Ychamberedhandle for receiving the conducting or mercury body. I also provide afusible plug in the rear end of the tumbler as a safety measure toprevent accidental breaking of the tumbler in the hand of an operator.The switch of my invention also embodies other improvements in theconstruction and arrangement of the mercury tumbler and its cooperatingelements.

In greater detail, and referring particularly to Figures 1 and 2, a formof switch embodying the improvements of my invention comprises arecessed base or frame 2 having straps I provided for mounting the basein" the wall oi a building. The base 2 may be of any suitable material,such as porcelain. The straps 3 of the frame also provide a mounting forthe wall plate 4 of the switch. This plate is preferably flush with thewall in which the switch is mounted, and may be of any suitablematerial, such as metal or a molded composition product; it beingunderstood that the particular form or composition of the plate l, likethat of the frame 2, may be varied within Wide limits.

A hollow tumbler or container 6 is mounted on the-base 2 for movementbetween open and closed switch positions. The tumbler is positioned withits rear end behind the Wall plate and with its front end projectingthrough the plate to provide a handle for operating the switch. Themounting for the tumbler preferably comprises a pair of resilientbrackets 1 projecting from the base 2 and terminating in sockets forreceiving suitable studs or trunnions 8 projecting from the sides of thetumbler. Note Figures '5 and 6 in conjunction with Figures 1 and 2 fordetails of this construction. 'I'he brackets 1 are of an electricalconducting material, such as metal, as are the studs 8, and the latterextend through the walls of the tumbler to provide contacts 9. NoteFigure 5. Each bracket, as best shown in Figure 6, is provided with abinding screw it! for attaching a circuit wire.

It wiil be understood that in addition to providing a releasable pivotmounting for the turnbier, the brackets and studs cooperate to form anelectrical connection between the external binding screws iii andcontacts 9 located within the tumbler. This construction provides asimple compact mounting `for the tumbler which is t both electricallyand mechanically, and by ch the tumbler may be removed by simply pullingthe saine out from between the brackets, or inserted by pressing thesame into position. While li have shown studs 8 having bevelled endsseating in sockets formed in the ends of the brackets l. it isunderstood that this is merely for illmtration and may equally as wellbe substi-s tuted by a construction in which nipples on the bracketsengage recesses or sockets formed in the ends of studs.

Referring again to Figures l and 2, i provide a coruiuctinfr body li,such as mercury, within the tumbler for bridging the contacts u in theciosed switch position of the tumbler. This body oi' mercury .is adaptedto flow-along the bore i2 of the tumbler when the latter moves back andbetween the upwardly extending or closed i position, as shown in Figure2, and the downwardly amending or open switch position, as shown inFigure l. The body of mercury is confined in the tumbler by a closurecomprising a plate or disk i3, preferably of mica, seated in an eniargedend of the bore i2 to provide a cup in which a @lling of sealing wax isprovided to form a fusible plug i4.

En assembling the tumbler unit of my switch both the mercury and tumblerare preferably heated to dry out the moisture before the tumbler issealed. After the mercury has been poured into the tumbler the disk I3is inserted and the cup provided thereby filled with molten sealing wax.This method -of assembling the tumbler of my invention not onlyprecludes the. presence of moisture within the tumbler, but also createsa partial vacuum within the tumbler when the elements have cooled.

In addition to providing a simple and effective means for sealing themercury within the tumbler, the closure comprising the sealing wax plugI4 provides an important safety feature. If the switch should beaccidentally overloaded ,the heat and pressure developed within thetumbler will soften the fusible plug I4 and blow the closure as well asthe mercury out through the rear end of the tumbler, This eliminates anypossibility of a pressure developing and breaking the forward or handleend of the tumbler and blowing the hot mercury into the hand of anoperator.

'Ihe recess of the porcelain base 2 covered by the wall plate 4 providesa safe receptacle for receiving the blown elements of the switch. An-

other important feature of my switch construction is that the circuitthrough the switch is opened immediately upon the blowing ut of the yeconomical and workable construction of thc switch is due largely to thefact that the mercury chamber projects through the wall plate and intothe handle portion of the tumbler. The chambered handle provides areservoir for receiving the mercury in the open switch position. and itis this maximum utilization of available space in the tumbler that makesmy toggle type of mercury switch possible.

From all outward appearances the switch of my invention cannot bedistinguished from the ordinary mechanical type of toggle wall switch,yet it is of simpler construction and has all the advantages offered bya mercury switch, such as silence of operation and absence of a nakedarc. The tumbler 6 is preferably of a moldable material, such as glassor urea-resin. I have used the latter composition with particularly goodresults. It presents a good appearance. and nossesses the necessarydielectric characteristics.

Figures l and 2 further illustrate the inclusion oi means for retardingthe flow of mercury from the closed switch position. This means ispref-- erably in the nature of a stationary barrier comprising ablock-like insert which may be slipped into the tumbler. The barrier isshown in detail in Figure 3 and preferably comprises a moldableinsulating material, such as ureau'esin, having a sloping forward wallI6 providing an inclined channel for the mercury ilow from the open tothe closed switch position, and a vertical back wall il! to block themercury flow from the closed to the open switch position.

A groove id is formed along the bottom oi the barrier to provide a ductthrough which the mercury may flow slowly back to the open switchposition. ln other words, the barrier or insert I5 provides asubstantially free passage for the mercury flow in one direction and arestricted passage for flow in the opposite direction. When the tumbleris thrown to the upwardly extending position the mercury will washfreely over the incline plane I6 and into the rear end of the tumbler tosubstantially instantaneously bridge the contacts 9 and close thecircuit through the switch. When the tumbler is moved to the downwardlyextending position however the flow of mercury is blocked by thebarrier, and will flow to the forward or handle end of the tumbler onlyas it is permitted to bleed out through the passage I8.

By means of this time delay action a. lamp in circuit with the switchwill stay lit`for a predetermined interval after the switch has beensnapped off. The amount of time required for the mercury to bleedthrough the restricted passage I8 determines the interval before thecircuit is opened and the light extinguished. For ordinary purposes in ahome the time required to cross a room, or retire into bed, willdetermine the delay action. 'I'his delay, depending upon the rate ofbleeding through the passage I8, may of course be varied within widelimits. It is understood of course that the delay may be effected fromthe on instead of from the oil position. Such a time delay switch isuseful in photographic work.

Means are also provided for dividing the mer- Cil cury between thecontacts before it has left either contacts it is lgradually split andfinally severed by the partition before the mercury has left eithercontact. Any arcing present in the switch therefore takes place in themercury rather than between the mercury and the contacts.

The partition I9 is preferably formed integrally with the insert orbarrier i5. Note Figure 3. As best shown in Figures 1 and 2 the barrierI5 is insertably positioned in a rectangularly cored portion of thetumbler and is locked securely in position by the plate I3 bearingagainst the rear edge of the partition portion i3.

A modified form of time delay switch embodying the improvements of myinvention is shown in Figures 4 and 5. In this construction a movablebarrier in the nature of a ball 22 is provided. 'I'he ball may be of anysuitable material, such as glass, and is adapted to seat against ashoulder provided by the reduced forward portions of the bore 23. 'I'heball operates as a check valve and provides a substantially free passagefor the iiow of mercury to the rear end of the tumbler, but blocks thepassage of mercury in the opposite direction. A bleeding action past theball 22 is provided by a groove 2l cored in the bottom of the tumbler.'I'he partition between the contacts in this case preferably comprises anotched panel 25 insertably mounted in suitable grooves cored in thetumbler, and is locked in place'by the plate i3 behind the wax plug Il.

Figure 6 illustrates another form of my invention. This switch does notcontemplate a time delay action, and the means for dividing the mercurybetween the contacts preferably comprises a notched partition insertablymounted in and extending longitudinally of the tumbler. Of course it isunderstood that the partition may be formed integrally with the tumbler,as shown in my copending application Serial No. 511,537, filed January27, 1931.

An important feature illustrated in Figure 6 is the quick-acting meansfor shifting the tumbler from one to the other of its switch positions.A tensione'd spring 21 is preferably connected between a lip 28 knockedout from the bracket 1 and a pin 29 formed on the flange of the stud l.The spring is positioned so that it passes over the pivot axis of thetumbler when the latter moves from one to another of its positions. Thespring therefore operates to hold the tumbler in a given position, andtl. snap the tumbler into a new position whenever the unbalanced springpasses over center. Preferably a spring is provided on each side of thetumbler.

T'his quick-acting means for the tumbler is of particular importance ina mercury type of switch, since it initiates a rapid flow of the mercurybody into and out of the closed switch position. This causes a rapidmake and break and reduces the period of arcing. Another importantfunction of the springs 21 is that of providing additional paths forcarrying current from the binding screws I0 to the contacts 3. Thebrackets 1 and studs 8 have adequate current carrying capacities per se.It is the bearing connection between these elements that forms theweakest link.

The springs 21 bridge this link and provide an additional path forcarrying current. A good conducting spring metal. such asphosphorbronze, is preferably used in these springs.

Other improvements embodying my invention are shown in Figure 7. In thiscase a pair of cups or recesses 3| are provided in the base end of thetumbler for retaining pools of the mercury. A pin 32 on the flange ofeach of the studs l provides a contact with the mercury in the pool. A

passage 33 communicating with the upper edges of thepools and extendingforwardly into the handle portionl of the tumbler provides a chamber forreceiving a portion of the mercury in the open switch position.

When the tumbler is moved upwardly this mercury flows back along thepassage 33 and washes over the cups or pockets 3| to bridge the mercurycontained therein. By this arrangement the circuit is made and broken inthe mercury, as in the previous cases. 'I'he present constructionhowever has the disadvantage of contacts permanently immersed in themercury, so that there is always the possibility of a leak completingitself across the partition between the pockets 3i to short the switch.In my other forms there is no possibility of a short being createdacrossthe contacts when the tumbler is in the open switch position,since the mercury at that time isy 'tion of the bore is V-shaped, sothat the `studs l present sloping contacts 31 upon which the ball 34 mayride. In the closed switch position the weighted ball rests upon thecontacts 31 to complete the circuit through the switch.

In conclusion it is pointed out that the noiseless action of my switchmakes it particularly desirable for use in hospitals. The externallyarcless feature eliminates fire hazard and improves ythe switch for alluses, and particularly in the presence of inflammable gases such as inservice stations. The fuse action in my switch makes it possible tosafely use portions of the mercury container itself as the handlefor-operating the switch. The chambered handle projecting through thewall plate for receiving the conducting body in one of the switchpositions is a feature of construction which permits the making of amercury switch in simulation of that toggle type flush wall switch,without exceeding the overall dimensions now standardized in suchswitches.

I claim:

l. A switch comprising a tumbler having a bore therein, a body ofmercury in the tumbler, a plate across the bore adjacent its opening toprovide a cup, and a body of fusible material in the cup for closing thebore.

2. A switch comprising a wall plate, a hollow tumbler having a baseportion positioned behind the wall plate and having an elongated portionprojecting through the plate to provide a handle, electrical conductingbrackets terminating in bearings and mounted behind the wall plate.electrical conducting trunnions on the tumbler mounted on the baseportion behind the wall plate and journaled in said bracket bearings formounting the tumbler for pivotal movement between open and closed switchpositions and extending into the tumbler to provide contacts` a body ofconducting fluid in the tumbler for closing the circuit through thecontacts, and electrical conducting springs connected between thebrackets and trunnions for snapping the tumbler from one to the other ofsaid switch positions.

3. A switch comprising a w'all plate, a tumbler mounted back oi' theplate for movement between open and closed switch positions and havingan elongated portion projecting through the plate to provide a handle,said tumbler having a longitudinal bore extending from the rear end ofthe tumbler and projecting into the elongated portion to provide achambered handle outside the wall plate, contacts in the tumbler behindthe wall plate, a body of conducting iluid in the tumbler for bridgingthe contacts in the closed switch position and ilowable along the boreand into the chambered handle in the open switch position, a cover plateacross the bore behind the contacts, and a body of fusible material inthe bore behind the cover plate to seal the tumbler.

4. A switch comprising a wall plate, a tumbler mounted back of the platefor movement between open and closed switch positions and having anelongated portion projecting through the plate to provide a handle',said tumbler having a longitudinal bore extending from the rear end ofthe tumbler and projecting into the elongated portion to provide achambered handle outside the wall plate, contacts in the tumbler behindthe wall plate, a body of conducting iiuid in the tumbler for bridgingthe contacts in the closed switch position and owable along the bore andinto the chambered handle .in the open switch position, means fordividing the fluid between the contacts and behind the wall plate, acover plate across the bore lbehind the contacts, and a body of fusiblematerial in the bore behind the cover plate to seal the tumbler.

5. A switch comprising a wall plate, a tumbler mounted back of the platefor movement between open and closed switch positions and having anelongated portion projecting through the plate to provide a handle, saidtumbler having a longitudinal bore extending from the rear end of thetumbler and projecting into the elongated portion to provide `achambered handle outside the wall plate, contacts in the tumbler behindthe wall plate, a body of conducting fluid in the tumbler for bridgingthe contacts in the closed switch position and flowable along the boreand into the chambered handle in the open switch position, means fordividing the fluid between the contacts and behind the wall plate, saidbore being enlarged behind the contacts to provide a shoulder, a coverplate across the bore and seated against said shoulder, and a body offusible material in the enlarged portion of the bore behind the coverplate to seal the tumbler.

6. A switch comprising a wall plate, a tumbler mounted back of the platefor movement between open and closed switch positions and having anelongated portion projecting through the plate to provide Ia handle,said tumbler having a longitudinal bore extending from the rear end ofthetumbler and projecting into the elongated portion to provide achambered handle outside the wall plate, contacts in the tumbler behindthe wall plate, a body of conducting iiuid in the tumbler for bridgingthe contacts in the closed switch position and ilowable along the boreand into the chambered handle inr the open switch position, a partitioninsertably mounted in the tumbler and extending longitudinally of thebore for dividing the fluid between the contacts, a cover plate acrossthe bore behind the partition to hold the latter in place, and a body offusible material in the bore behind the cover plate to seal the tumbler.

"1. A switch comprising a wall plate. a tumbler mounted back of theplate for movement between open and closed switch positions and havingan elongated portion projecting through the plate to provide a handle,said tumbler having a longitudinal bore extending from the rear end ofthe tumbler and projecting into the elongated por tion to provide achambered handle outside the Wall plate, contacts in the tumbler behindthe Wall plate, a body of conducting iiuid in the tumbler for bridgingthe contacts in the closed switch position and flowable along the boreand intov the chambered handle in the open switch position, a barrierinsertably mounted in the bore between the contacts and the handle endof the tumbler for restricting the iiow of said fluid, a partitioninsertably mounted in the bore and extending rearwardly of the barrierfor dividing the fluid between the contacts, a cover plate across thebore behind the partition for holding the latter and the barrier inplace, and a body of fusible material in the bore behind the cover plateto seal the tumbler.

8. A switch comprising a wall plate, a tumbler' mounted back ofthe platefor movement between open and closed switch positions and having anelongated portion projecting through the plate to provide a handle, saidtumbler having a longitudinal bore extending from the rear end of thetumbler and projecting into the elongated portion to provide a chamberedhandle outside the wall plate, contacts in the tumbler behind the wallplate, a body of conducting fluid in the tumbler for bridging thecontacts in the closed switch position and ilowable along the bore andinto the chambered handle in the open switch position, said bore beingenlarged rearwardly of its intermediate portions to provide a shoulderforwardly of the contacts, a barrier in the bore and seated against saidshoulder for restricting the flow of said fluid, a partition in the borebehind the barrier for dividing the fluid between the contacts, a coverplate across the bore behind the partition, and a body of fusiblematerial inthe bore behind the cover plate to seal the tumbler.

9. A switch comprising a wall plate, a tumbler mounted back of the platefor movement between open and closed switch positions and having anelongated portion projecting through the plate to provide a handle, saidtumbler havin a longitudinal bore extending from the rear end' of thetumbler and projecting into the elongated portion to provide a chamberedhandle outside 'the wall plate, contacts in the tumbler behind the wallplate, a bodyof conducting uid in the tumbler lfor bridging the contactsin the closed switch position and flowable along the bore and into thechambered handle in the open switch position. said bore being enlarge/drearwardly of its intermediate portions to provide a shoulder forwardlyof the contacts, a barrier insertably mounted in the bore and seatedagainst said shoulder for restricting the ilow of said fluid, apartition formed integrally with the barrier and extending rearwardlytherefrom for dividing the fluid between the contacts, a cover plateacross the bore behind the partition for holding the latter and thebarrier in place, and a body of fusible material in the bore behind thecover plate to seal the tumbler.

l0. A switch comprising a wall plate, a tumbler mounted back of theplate for movement between open and closed switch positions and havingan elongated portion projecting through the plate to provide a handle,contacts ln the rear end of the tumbler behind the wall plate, saidtumbler having al bore extending from the rear end of the tumblerbetween the contacts, a body of conducting iluid in the tumbler forbridging the contacts in the closed switch position, a partition in thebore for dividing the fluid between the contacts and behind the wallplate, a cover plate across the bore behind the partition, and a body offusible material in the bore behind the cover plate to seal the tumbler.

11. A switch comprising a chambered tumbler mounted for movement betweenopen and closed switch positions, contacts in the chamber, a body ofmercury ilowable in the chamber for bridging the contacts in the closedswitch position, means extending transversely across the chamber forrestricting the ilow of mercury from the closed to the open switchpositions, and a partition extending longitudinally of the chamber fordividing the mercury to open the circuit.

12. A switch comprising a wall plate, a hollow tumbler mounted behindthe wall plate and having an elongated portion projecting through theplate to provide a handle, contacts in the tumbier, a body o! mercuryflowable in\ the tumbler for bridging the contacts, means forrestricting the flow of mercury away from the contacts, and means behindthe restricting means for dividing the mercury between the contacts toopen the\ circuit before all the mercury has bled past the restrictingmeans.

13. A mercury switch comprising a. hollow tumbler, oppositely disposedjournals adjacent one end of the tumbler for mounting the latter forpivotal movement and extending into the tumbler to provide contacts, abody of mercury in the tumbler for bridging the contacts and flowableaway from the latter to open the circuit, means positioned across thetumbler ahead of the contacts for restricting the flow o! mercury awayfrom the contacts, and a mercury severing partition Abehind therestricting means and arranged between the contacts for dividing themercury to open the circuit while the mercury is bleeding past therestricting means.

WALTER. MURAD.

